This invention relates to a paper battery and more particularly to a paper battery of the type having positive and negative electrode plates respectively contacting positive and negative electrodes protruding in the same direction and a sealing agent on these plates for sticking them together.
There have been electronic devices such as IC cards that incorporate a thin paper battery as a backup power source. As shown in FIG. 5, such a device is typically composed of a central processing unit (CPU) 11 and a random access memory device (RAM) 12, using main batteries 13 as the principal source of power and a paper battery 14 which serves as a backup power source. Numerals 31, 32 and 33 represent a data bus, an address bus and a control bus, respectively. Numerals 15 and 16 represent respectively a backup capacitor and diodes for preventing a current from flowing in the wrong direction.
The paper battery 14 is structured, as shown in FIGS. 6 and 7, with a positive electrode plate 17, a negative electrode plate 18 and a sealing agent 19 which is sandwiched therebetween and serves to hold them together. The plates 17 and 18 are so structured as to be in contact respectively with a positive terminal 20 and a negative terminal 21 protruding in the same direction with respect to each other.
FIG. 7 shows a sectional view when the paper battery 14 has been set correctly in the circuit shown in FIG. 5. It happens not infrequently, however, that the user inserts the paper battery 14 in upside-down direction. If the paper battery 14 is thus inserted erroneously as shown in FIG. 8, both the positive and negative terminals 20 and 21 come into contact with the negative electrode plate 18 such that there results a short circuit between the grounding terminal GND and the source voltage terminal V.sub.CC of the random access memory 12 as well as between the positive and negative terminals of the aforementioned backup capacitor 15. As a result, data stored in the random access memory 12 are destroyed.